SpatioSpatio--Temporal Dynamics of SAV Temporal Dynamics of SAV Abundance and Water Quality in the Abundance and Water Quality in the Mangrove Lakes Region of Florida BayMangrove Lakes Region of Florida Bay
Thomas A. FrankovichThomas A. Frankovich11, James W. Fourqurean, James W. Fourqurean11,,Douglas MorrisonDouglas Morrison22
11 Florida International UniversityFlorida International University22 Everglades National ParkEverglades National Park
GEER 2008, July 27 GEER 2008, July 27 –– August 1, Naples FL.August 1, Naples FL.
Where are the Mangrove Lakes?Where are the Mangrove Lakes?
USGS
ImportanceImportance
Extensive SAV beds (historically)
Critical habitat for American crocodile
Wintering area for waterfowl
Photos courtesy D. Chalfant, naturepicsonline, AnimalPlanet
Ruppia maritima
Blue-winged teal
American coot
Study ObjectivesStudy Objectives
To identify relationships between waterquality and benthic macrophytes
To use the identified relationships topredict changes in benthic macrophytedistribution and abundance that may result from changes in water qualityproduced by restoration efforts
Sp. ASp. B
Water quality
MethodsMethods
SAV % cover, quarterly (41 sites)- 1/4 m2 quadrat (5% intervals)- all benthic macrophytes- 15 replicates per site
WQ monitoring, monthly- temp, sal, water depth, secchi depth (41 sites)- TotN, TotP, Phytoplankton chl-a (each basin –8 sites)
Hourly water temperature, salinity, and water level- datasondes in West Lake, The Lungs, 7 Palms Lake
Data collection ongoing – April 2006 – April 2009
Study SitesStudy Sites
StatisticsStatistics
Exploratory statistics
- Cluster analysis- NMS ordination- Regression analyses
Statistical model
- Discriminant Function Analysis- Logistic Regression
1 1 111 1
22 2 22
333 3 3
Results Results –– Benthic macrophytesBenthic macrophytes
Chara Hal. Bat. Ruppia Acet. OtherPrevalence (%) 4646 3939 30 20 11 8Rel. abundance (%) 5858 3030 9 2 <1 <1
Acetabularia sp.Halodule wrightii
Batophora oerstedii
Other – Halimeda incrassata, Penicillus capitatus, Sargassum pteropleuron,Laurencia sp.,Thalassia testudinum, Polysiphonia sp., Caulerpa prolifera, Rhizophora mangle
Chara and Halodule dominate species assemblages
Chara hornemanni
Results Results –– Benthic macrophytesBenthic macrophytes
Sites grouped according to differences in community structure
S27
S41
S10
S40
S16
S18
S15
S37
S36
S17
S14
S21
S19
S39
S20
S38
S22
S33
S13
S34
S11
S12 S
9S
8S
5S
7S
28S
32 S4
S23
S24
S35
S29
S25
S30 S
2S
3S
1S
26 S6
S31
Sam ples
100
80
60
40
20
0S
imila
rity Halodule
Chara
Low abundanceHigh abundance
Results Results –– Benthic macrophytesBenthic macrophytes
Chara characterizes upstream lakesHalodule characterizes coastal embayments
Species distribution
Results Results –– Benthic macrophytesBenthic macrophytes, salinity, salinity
Salinity distribution (mean 2006 – 2008)
Species (Chara, Halodule) differentiate along salinity gradient
Results Results –– Benthic macrophytesBenthic macrophytes
NMS axis 1-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
NM
S a
xis
2
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
Salinity CharaHalodule
Florida Bay
West system
7 Palms system
Salinity r2 = 0.65
Stress = 10.7
Differences in community structure are evident betweenFlorida Bay sites, West system sites, and 7 Palms sites.
Results Results –– Benthic macrophytesBenthic macrophytes
Chara
Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul
Mea
n Pe
rcen
t Cov
er
0
10
20
30
40
50
60
Halodule
2006 - 2008
Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul
Mea
n Pe
rcen
t cov
er
0
10
20
30
40
50
60
Chara percent cover is minimumin summer and fall and peaks inwinter and spring.
Halodule percent cover is minimum in winter and springand maximum in summer and fall.
Seasonality is evident in Charaand Halodule, but timing is asynchronous.
Results Results –– Temperature, salinityTemperature, salinityWest Lake
Jun Sep Dec Mar Jun Sep Dec Mar Jun
Tem
pera
ture
(C)
10
15
20
25
30
35
40
Jun Sep Dec Mar Jun Sep Dec Mar Jun
Sal
inity
(ppt
)
0
10
20
30
40
50
7 Palms Lake
Jun Sep Dec Mar Jun Sep Dec Mar Jun
Tem
pera
ture
(C)
10
15
20
25
30
35
40
Jun Sep Dec Mar Jun Sep Dec Mar Jun
Sal
inity
(ppt
)
0
10
20
30
40
50
Water temperature – maximum in summer, minimum in wintersalinity increases during dry season (winter-spring), decreasesduring summer and fall.
Results Results –– NutrientsNutrients
7 Palms Lake System
Apr Jul Oct Jan Apr Jul Oct Jan Apr
Tota
l Nitr
ogen
(μm
)
0
50
100
150
200
2507 Palms Lake Site 2Middle Lake Site 8Monroe Lake Site 13Terrapin Bay Site 17
West Lake System
2006 - 2008Apr Jul Oct Jan Apr Jul Oct Jan Apr
Tota
l Nitr
ogen
(μm
)
0
50
100
150
200
250West Lake Site 28Long Lake Site 30The Lungs Site 35Garfield Bight Site 40
7 Palms Lake System
Apr Jul Oct Jan Apr Jul Oct Jan Apr
Tota
l Pho
spho
rus
(μm
)
0
2
4
6
8
10
7 Palms Lake Site 2Middle Lake Site 8Monroe Lake Site 13Terrapin Bay Site 17
West Lake System
2006 - 2008Apr Jul Oct Jan Apr Jul Oct Jan Apr
Tota
l Pho
spho
rus
(μm
)
0
2
4
6
8
10
West Lake Site 28Long Lake Site 30The Lungs Site 35Garfield Bight Site 40
Spatial variation in nutrient concentrations more evident thanseasonal variation. More nutrients in West Lake system.Phosphorus limitation less severe in West Lake system.
N:P ≈≈ 90:190:1
N:P ≈≈ 30:130:1
Results Results –– phytoplanktonphytoplankton
7 Palms Lake System
Chl
orop
hyll
a (u
g L-1
)
0
20
40
60
7 Palms Lake site 2Middle Lake site 8Monroe Lake site 13Terrapin Bay site 17
West Lake System
2006 - 2008Jun Sep Dec Mar Jun Sep Dec Mar Jun
Chl
orop
hyll
a (u
g L-1
)
0
20
40
60
West Lake site 28Long Lake site 30The Lungs site 35Garfield Bight site 40
Phytoplankton abundances 6X greater in West Lake system
Results Results –– phytoplanktonphytoplankton
Phytoplankton Chlorophyll vs Total Phosphorus
Total phosphorus (μM)0 1 2 3 4 5 6
Chl
-a (
μ g L
-1)
0
20
40
60r2 = 0.46P < 0.001
7 Palms Lake system West Lake system
Phytoplankton abundance correlated with P-availability
Results Results –– Benthic macrophytesBenthic macrophytes
Chara abundance
Perc
ent C
over
0
20
40
60
80
100
West system7 Palms system
Water Clarity
Wat
er c
larit
y in
dex
0
1
2
3
4
Water Clarity Index
Secchi depth1 0 – 20 cm 2 20 – 40 cm3 40 – 60 cm4 > 60 cm
Greater Chara abundance associated with increased water clarity
Key findings Key findings –– preliminary conclusionspreliminary conclusions
Spatial species distribution consistent with mean salinity.
Seasonality of Chara and Halodule abundances asynchronous.
P concentrations are ≈3X greater in West Lake systemthan in 7 Palms system, fueling ≈6X greaterphytoplankton densities.
Greater water clarities in 7 Palms system coincidewith ≈5X greater Chara abundances relative toWest Lake system.
Acknowledgments
We thank: Dr. Bill Loftus for use of jonboat
Steven Huddleston, Jeff Woods, Mark Zucker (USGS) for field collaboration
many, many other field volunteers
Funding provided by Everglades National ParkFunding provided by Everglades National Park
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